<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container{
            width: 200px;
            height: 200px;
            background-color: #888;
            position: relative;
            margin-left: 100px;
        }

        .box{
            width: 100px;
            height: 100px;
            background-color: purple;
            position: absolute;
            left: 50px;
            top: 50px;
        }
    </style>
</head>
<body>
    <div class="container">

        <div class="box"></div>
    </div>
</body>
</html>